There are known an exhaust gas purifying device, which is interposed in an exhaust-gas flow path of an internal combustion engine in a gasoline engine, a diesel engine and the like, to purify an exhaust gas by a catalyst or the like, and an exhaust silencing device by which an exhaust noise is reduced. As such type of device, there is known a device in which a flow channel pipe is inserted into a cylindrical shell from a radial direction thereof and is connected to an exhaust-gas flow path, thereby generating a flow channel through which an exhaust gas flows, as described in Japanese Unexamined Patent Application Publication No. 2005-330839.